Product guide: oils

What is extra virgin olive oil?The highest quality olive oil there is. In taste, nutritional content, texture and aroma, extra virgin is superior to virgin olive oil, olive oil and refined olive oil—and its value is enshrined in law. “According to EU regulations, there are various factors that must go into the production of extra virgin olive oil,” explains Marianna at Oliveology.

“It must be cold extracted—below 27C—within 48 hours of harvesting the fruit.” Longer than that, and it’s no longer extra virgin. “The olives get bruised if they sit for days in a container. This affects the final product.” The result should be a smooth, rich oil with an acidity level below 0.8 per cent. But even within the extra virgin category there are significant variations in quality.

How so?“We press within two hours and in smaller batches. This makes a big difference,” says Marianna. “Our acidity level is very low—about 0.1 per cent.” The exact heat at which the olives are pressed is also a major factor, which is why all Oliveology’s extra virgin oils are prominently branded with the temperature of the extraction, ranging from 18C to 27C.

“Extra virgin olive oil contains delicate compounds which are destroyed at high temperatures; the colder the temperature of extraction, the better the quality and the higher the nutritional value.” At lower temperatures, you need more olives to produce the same quantity of oil, so the lower the heat, the higher the production cost.

How do you decide what oil to use? Different oils suit different purposes. “These are good for dipping, taking spoonfuls for health benefits—even lathering on your face,” says Marianna, pointing to her coldest oils, but you probably wouldn’t want to cook with them. Her most versatile extra virgin, pressed at 27C, is good for cooking with, as well as dressings and dips. Richer oils work best when paired with strong flavours—garlic or chilli, for example.

De Calabria’s popular carolea extra virgin works particularly well on bruschetta, greens and white meats. “Carolea olives, compared to the many other varieties, have far more pulp—the texture is smoother and creamier,” says stallholder Giuseppe.

Do they vary a lot in taste and texture?Absolutely. “Olive oil is like wine—it has a completely different taste according to the variety, the region, the microclimate, when it is picked—even the elevation and soil,” Marianna explains. Most of the olive oil sold in Borough Market is single estate, monovarietal oil. “It means you get a better taste—a typical taste of the locality and the season, preserved in the oil,” agrees Danilo, whose The Olive Oil Company sells single estate oils from around Italy. “I like single estate olive oil for similar reasons as I like single malt whisky,” says Marianna. “You get the authentic taste and character of the particular region in every possible way.”

Subtle variations can exist even at a single estate level. “We have four different olive oils produced by the same variety of olive, on the same estate—but they differ according to ripeness. Each oil has two to three weeks’ difference in picking time, and that changes the flavour,” says Marianna. Geography can also make a difference: “One slope might get more sunshine, one might have more moisture in the soil,” says Giuseppe. “The result is a different oil.”

The extra virgin olive oil in Borough Market is often darker than that in supermarkets. Why?“Because it is not processed; it is the same as it was when it came out of the press,” says Giuseppe. “This means there’s a small bit of sediment in there: seeds, skin, even bits of leaves.” To Giuseppe this is integral. “When you refine and process rice and wheat to make it white, you lose much of the goodness. It’s the same thing with oil when it’s highly filtered.”

Those micro-particles which lend the oil its colour are nutritious and flavourful—but they aren’t that attractive if you’re used to the green clarity of a shop-bought product. Many of Borough Market’s traders choose to rely on a natural filtering system—they just wait for the sediment to sink to the bottom of the main tank before drawing it off into bottles. Some of that delicious impurity remains, but not enough to make the oil unsightly, or affect its use-by date.

What about infused oils? What do they add to the mix?Bags of flavour. Dawn from Pimento Hill produces a garlic and herb oil at her east London kitchen, using rapeseed oil from Kent, into which these punchy flavours are slowly infused. The Olive Oil Company’s chilli oil meanwhile, is quite different.

“We crush fresh chillies together with the olives, so it is not like most infused oils,” says Danilo. “The chillies come from the same estate as the olives.” Though not suitable for cooking with, the sky is the limit when it comes to drizzling. “Best served on pizza, pasta, cheese and onion sandwiches, prawns,” Danilo lists. “Anywhere, really, where you wish to add a kick!”

What is linseed oil? It is made from pressing tiny linseeds—also known as flaxseeds. “We grow all our linseed ourselves in Sussex,” says Sarah from Flax Farm. “We cold press the seeds, so we don’t oxidise the oil and reduce its nutritional benefits.”

There are many ways in which to indulge in its goodness. “It has a lovely, light grassy flavour—not unlike butter—and makes an excellent mayonnaise.” Stir it in mashed potato or use it to lift the flavour of your soups. If you’re vegan, explore it as an egg alternative. “We’ve had great success using it in some of our cakes,” says Sarah.